Method of producing a resinous condensation product



r N 2,735,838 Ice Patented Feb. 21, 1956 METHOD OF PRODUCING A RESINOUSCONDENSATION PRODUCT Rinse Dijkstra and Jelis de Jonge, Eindhoven,Netherlands, assignors to Hartford National Bank and Trust Company,Hartford, Conn., as trustee No Drawing. Application June 19, 1953,Serial No. 362,966

Claims priority, application Netherlands June 11, 1952 i 6 Claims; (Cl.260-56) Our invention relates to the production of resinous condensationproducts of the phenol furfural type.

More particularly, our invention relates to resinous condensationproducts produced by heating furfural and phenol, i. e.,monohydroxybenzene and alkyl derivatives thereof, with an alkalinesubstance acting as a catalyst, such as ammonia, alkali and alkalineearth hydroxides, alkali carbonates, tertiary amines, for exampletriethyl amine and dimethyl aniline, and melamine and methylolderivative of melamine, the condensation reaction with the formation ofwater preferably proceeding so long as is compatible with the furtherworking up of the resinous product.

It is known that in working up phenol-aldehyde'condensation productsinvolves difliculties if the quantity of aldehyde combined with phenolwith the formation of water exceeds about 1 mol. aldehyde per mol.phenol. Consequently, it is desirable to obtain such condensationproducts wherein phenol has reacted with furfural with the formation ofonly little less than 1 mol. water per mol. phenol.

It has been described that the production of such phenol furfuralcondensation products entails difliculties chiefly because thecondensation reaction proceeds extremely slowly at a low temperature,for example 110 C., and at a higher temperature, for example 140 C. to160 C., the condensation product becomes intractable even before thecondensation reaction has proceeded to the desired point.

Our invention resides in a method of obtaining, at an increasedtemperature, resinous, moderately viscous condensation products, inwhich furfural has reacted with a phenol, by warming a phenol togetherwith furfural in the presence of an alkaline substance acting as acatalyst, in which at most 0.1 mol. catalyst per mol. phenol is added tothe reaction mixture partly for starting up the condensation reactionand partly during this reaction, the condensation reaction being allowedto proceed until a little less than 1 mol. water per mol. phenol hasbeen split off.

The method according to the present invention is generally not so veryeffective, in that the viscosity of the resulting condensation productis not significantly lowered, if an active catalyst such as an alkalimetal hydroxide and an alkali metal carbonate is used.

Preferably, in carrying out the method according to the invention, aless active catalyst, for example alkaline earth hydroxide is used. Asan alternative amines, for example primary amines, are eminentlysuitable for this purpose.

In U. S. application Ser. No. 257,941 filed November 23, 1951, a processhas been described according to which ammonia or a primary amine iscaused to coreact with a phenol, furfural and a catalyst also yieldinghighly condensated products of low viscosity. According to this methodthe optimum proportion of ammonia or primary amine corresponds tobetween 0.1 and 0.2 mol. for each mol. of the phenol in the reactingmixture. In a further preferred example of the present invention use ismade of a quantity of ammonia of less than 0.1 mol. per mol. phenol and,after the condensation reaction has been started up by adding catalyst,still more catalyst is added during the condensation reaction.

We have found that the products obtained in the hardened state afterconversion of the phenol furfural condensation products possess agreater mechanical strength and shrink less on hardening if, during thecondensation reaction of phenol with furfural, the action of thecatalyst is supported by adding less than 0.1 mol. ammonia per mol.phenol.

The invention may be carried out in such manner that catalyst iscontinuously added to the condensing mixture. Since, however, it is notnecessary to use large quantities of catalyst, a quantity of a few gramsper mol. phenol being sufficient, it may be preferable to add a smallquantity of catalyst at regular time intervals to the reacting mixture.

By thus carrying out the method according to the invention acondensation product, in which per mol. phenol about 0.8 mol. furfuralcombines with the formation of water, can be obtained in three to fourhours during which time the temperature is raised from C. to 170 C.Therefore, the condensation preferably takes place at said temperatures.

Example I 2 mol. monohydroxybenzene were mixed with 12 g. .water, 1.8mol. furfural and 2.5 g. calcium hydroxide in a round-bottomed flask bymeans of. a stirrer and a distillation cooler. The mixture was rapidlyheated to 100 C. and further heated slowly so that the temperature roseto 160 C. in one hour, which temperature was maintained at 160 C. untilthe termination of the reaction. 30 minutes after the temperature in theflask had risen to 100 C. 1 g. calcium hydroxide was added and this wasthree times repeated at intervals of 15 minutes. After the lastadmixture the heating was continued for one hour and the reactionproduct subsequently poured out into a flat container. From the weightand the composition of the product of distillation it was determinedthat 0.77 mol. furfural had combined with the formation of Water. If thesame quantity of catalyst as used in total for the test had been addedin a single quantity, the formation of Water would proceed much moreslowly so that after eight hours the quantity of Water split off wouldhave been approximately equal and the reaction mixture would have becomeso viscous as to be intractable.

Example 11 2 mol. monohydroxybenzene, 12 g. water, 1.9 mol. furfural and0.08 mol. ammonia in the form of a 25% solution in water were warmedwith 2.5 g. calcium hydroxide in the manner as described in Example I.30 minutes after reaching a temperature of 100 C. 1 g. calcium hydroxidewas added, which was repeated four times at intervals of 15 minutes.minutes after reaching the temperature of 100 C. it was determined fromthe composition and quantity of product of distillation that per mol.phenol 0.83 mol. furfural had been linked with the formation of water.The reaction was subsequently interrupted and the thinly liquid mass,which solidified to a brittle resin after cooling, was mixed with woodflour and hexamethylene tetramine to form molding powder from which aplate (I) was molded. Similarly, a plate II was molded, in which acondensation product of monohydroxybenzene and furfural had beenincorporated, the conversion having been accomplished by an equalquantity of calcium hydroxide and 0.16 mol. ammonia per mol. phenol.

On molding the plate I shrunk 0.77% and the plate II 1.02%. Theresistance to shock of plate I was 2.4 kg./cm. that of plate II 2.0kg./cm. the said values being 7.5 and 7.0 kg/cm. respectively as regardsthe shock bending strength.

Example III Similarly to Example I, 2 mol. monohydroxybenzene, 12 g.water, 2% mol. furfural and 0.08 mol. ethylene diamine were mixed andheated in 40 minutes to 160 C. at which temperature the mixture wasmaintained until the reaction was interrupted. One hour after reachingthe temperature of 160 C., a further quantity of ethylene diamine of0.04 mol. was added, of which /8 part was added each time at intervalsof 10 minutes. minutes after adding the last quantity, the contents ofthe flask were poured out into a shallow container, in which itsolidified to form a brittle resin. From the quantity and thecomposition of the product of distillation it was determined that permol. monohydroxybenzene in the resin 0.92 mol. furfural had combinedwith the formation of water.

If, however, the same quantities of monohydroxybenzene and furfural werereacted at the same temperatures with a quantity of ethylene diamine of0.12 mol. added in a single quantity at the outset of heating, thequantity of Water formed in the same lapse of time resulted in not morethan 0.75 mol. furfural being condensed.

While we have thus described our invention with specific examples andapplications thereof, other modifications therein will be apparent tothose skilled in this art without departing from the spirit and scope ofthe invention as defined in the appended claims.

What is claimed is:

1. A method of producing a resinous condensation product of thephenol-aldehyde type which comprises mixing about one mole of phenoltogether with about one mole of furfural and less than 0.1 mole of analkaline catalyst and in an amount sufiicient to commence the reaction,heating the reaction mixture to a temperature of about to 170 C., addingan additional quantity of the catalyst in an amount which together withthe portion initially provided in the reaction mixture is less than 0.1mol. of the catalyst per mol. of the phenol, and terminating thereaction when less than 1 mol. water per mol. of phenol is split off.

2. A method as claimed in claim 1, in which the catalyst is an alkalineearth hydroxide.

3. A method as claimed in claim 2, in which a quantity of ammoniasmaller than 0.1 mol. phenol is added to the phenol furfural mixture.

4. A method as claimed in claim 3-, in which the condensation reactionis effected at a temperature of about and C.

5. A method as claimed in claim 1 in which the catalyst is a primaryamine.

6. A method as claimed in claim 5 in which the catalyst is ethylenediamine.

References Cited in the file of this patent UNITED STATES PATENTS1,705,495 Novotny Mar. 9, 1929 1,771,033 Ellis July 22,1930 1,857,357Cherry et al May 10, 1932 2,457,493 Redfern Dec. 28, 1948

1. A METHOD OF PRODUCING A RESINOUS CONDENSATION PRODUCT OF THEPHENOL-ALDEHYDE TYPE WHICH COMPRISES MIXING ABOUT ONE MOLE OF PHENOLTOGETHER WITH ABOUT ONE MOLE OF FURFURAL AND LESS THAN 0.1 MOLE OF ANALKALINE CATALYST AND IN AN AMOUNT SUFFICIENT TO COMMENCE THE REACTION,HEATING THE REACTION MIXTURE TO A TEMPERATURE OF ABOUT 120 TO 170* C.,ADDING AN ADDITIONAL QUANTITY OF THE CATALYST IN AN AMOUNT WHICHTOGETHER WITH THE PORTION INITIALLY PROVIDED IN THE REACTION MIXTURE ISLESS THAN 0.1 MOL. OF THE CATALYST PER MOL. OF THE PHENOL, ANDTERMINATING THE REACTION WHEN LESS THAN 1 MOL. WATER PER MOL. OF PHENOLIS SPLIT OFF.